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Energy & Power

The Museum's collections on energy and power illuminate the role of fire, steam, wind, water, electricity, and the atom in the nation's history. The artifacts include wood-burning stoves, water turbines, and windmills, as well as steam, gas, and diesel engines. Oil-exploration and coal-mining equipment form part of these collections, along with a computer that controlled a power plant and even bubble chambers—a tool of physicists to study protons, electrons, and other charged particles.

A special strength of the collections lies in objects related to the history of electrical power, including generators, batteries, cables, transformers, and early photovoltaic cells. A group of Thomas Edison's earliest light bulbs are a precious treasure. Hundreds of other objects represent the innumerable uses of electricity, from streetlights and railway signals to microwave ovens and satellite equipment.

This is the discharge unit for the third type of laser invented. Dr. Ali Javan and his colleagues William Bennett and Donald Herriott demonstrated this laser at Bell Labs in December 1960. Using a mixture of helium and neon gasses, this laser emitted a continuous beam of light at 1.153 nano-meters, in the near-infrared part of the spectrum. Their successful demonstration proved crucial for many applications. The first supermarket scanners, made by Spectra Physics, used a helium-neon laser, as have many other commercial devices.

Ali Javan came to the U.S. from Iran in 1948 and trained in the laboratory of maser inventor Charles H. Townes at Columbia University. When he received his Ph.D. in 1954, Javan went to work at Bell Labs where began investigating the possibility of making a laser using a gaseous medium. His laser was the first gas laser as well as the first laser to produce a continuous beam of radiation.

The apparatus that was used to produce the first Bose-Einstein Condensate (BEC) observed in a gas of atoms

In 1995, a group of physicists led by Eric A. Cornell and Carl E. Wieman produced the first BEC in a gas of 2000 rubidium atoms at the NIST–JILA laboratory at the University of Colorado at Boulder. Just about four months later, a group led by Wolfgang Ketterle independently produced a BEC with about 200,000 sodium atoms. Cornell, Wieman and Ketterle were awarded the 2001 Nobel Prize in Physics for their accomplishments.

The Cornell and Wieman BEC apparatus consisted of an atomic trap that cooled atoms by means of two different mechanisms. First, six laser beams cooled the atoms, initially at room temperature, while confining them near the center of an evacuated glass box. Next, the laser beams were turned off, and magnetic coils were energized. Current flowing in through the coils generated a magnetic field that further confined most of the atoms while allowing the more energetic ones to escape. Thus, the average energy of the remaining atoms decreases, making the sample colder and even more closely confined to the center of then trap. Ultimately, many of the atoms attain the lowest possible energy state allowed by quantum mechanics, and become a single entity – a BEC. Other research groups are now using BEC principles for investigations in the field of atom quantum optics, including quantum information processing and development of the atomic analogue of the laser.

The core components of the Cornell-Wieman BEC apparatus are in the Modern Physics Collection at the Smithsonian Institution’s National Museum of American History, in accession no. 1998.0213.

Background on the Bose-Einstein Condensate (BEC) phenomenon

[Adapted from “The Bose-Einstein Condensate,” E.A. Cornell and C.E. Wieman in Scientific American, March, 1998, pp 40-45; and from “Very Cold Indeed: The Nanokelvin Physics of Bose-Einstein Condensation,” Journal of Research of the National Institute of Standards and Technology, V. 101, Jul.–Aug. 1996, p. 419]

In June 1995, a team of scientists succeeded in cooling a gas of 2,000 rubidium atoms to a temperature less than 100 billionths of a degree above absolute zero, causing the atoms to lose for a full ten seconds their individual identities and behave as though they were a single “superatom.” That is, the atoms’ physical properties, such as their motions, became identical to one another. This Bose-Einstein Condensate (BEC), the first observed in a gas, can be thought of as the matter counterpart of the laser – except that in the BEC it is atoms, rather than photons of light, that behave in perfect unison (all going in the same direction with the same energy).

The BEC offers a macroscopic window into the strange world of quantum mechanics, the theory of matter based on the observation that elementary particles, such as electrons, have wave properties. Quantum mechanics uses these wavelike properties to describe the structure and interactions of matter. In ordinary macroscopic matter, the incoherent contributions of the large number of constituent atoms obscure the wave nature of quantum mechanics. But as atoms get colder, they start to behave more like waves and less like particles. Cool a cloud of identical atoms so cold that the wave of each atom starts to overlap with the wave of its neighbor atom, and all of a sudden one creates a BEC. In a BEC, the wave nature of each atom is precisely in phase with that of every other. Quantum mechanical waves extend across the collection of atoms, an image of which can be observed with the naked eye.

Some five decades earlier, physicists had realized that the BEC concept could explain superfluidity in liquid helium, which occurs at much higher temperatures than gaseous Bose-Einstein condensation. (Superfluidity is a state of matter in which the matter behaves like a fluid without viscosity and with extremely high thermal conductivity.) When it passes below a critical temperature, liquid helium makes the transition from an ordinary liquid to a superfluid and starts to behave like a quantum fluid. But the helium atoms in the liquid state interact quite strongly, and the system is difficult to understand on an elementary level. Thus, physicists had been pushing for many years to observe Bose-Einstein condensation in a system closer to the gaseous state.

Brief description of fermions and bosons, and Bose-Einstein statistics

All elementary particles, and even composite particles such as atoms, can be divided into bosons and fermions. [The spin of an elementary particle is a truly intrinsic physical property, akin to the particle's electric charge and rest mass, and is expressed as a spin quantum number.] Bosons are particles that have integer spin; 0, 1, 2, 3, and so on (in units of reduced Plank constant, h/(2π)). Fermions are particles that have half-integer spin: 1/2, 3/2, 5/2, and so on, in the same units. Examples of bosons are particles that transmit interactions (i.e., force carriers), such as photons (electromagnetic force), and a large portion of the atoms of individual chemical elements. Examples of fermions are particles that are the elementary building blocks of matter: electrons, protons, neutrons, and the quarks inside protons and neutrons. All atoms are composed of fermions, but if the atom consists of an even number of fermions, it will be a composite particle with integer spin, which is a boson. The new statistics (see below) was first studied in 1924 by Satyendra Nath Bose, so physicists call particles for which only symmetrical states occur in nature bosons. [According to the Oxford English Dictionary, the term “boson” was introduced by physicist Paul Dirac in 1947; P.A.M. Dirac Princ. Quantum Mech, (ed. 3) ix. 210.]

Fermions, the particles with half-integer spin obey Fermi-Dirac statistics. Accordingly, they occupy anti-symmetric quantum states; this property forbids fermions from sharing quantum states – a restriction known as the Pauli Exclusion Principle. Bosons, the particles with integer spin, on the other hand, obey Bose-Einstein statistics (see below). Accordingly, they occupy symmetric quantum states; this property allows bosons to share quantum states. Thus, the latter property allows a collection of identical atoms that are bosons to be cooled to the same quantum state, which is termed a BEC.

Satyendra Nath Bose (1 January 1894 - 4 February 1974) was an Indian mathematician and physicist, best known for his work on quantum mechanics in the early 1920s, which provided the foundation for Bose–Einstein statistics and the theory of the BEC. Specifically, Bose developed a statistical model, based on a counting method that assumed that light could be understood as a gas of indistinguishable quanta or particles. Bose is honored as the namesake of such a particle, a boson

Albert Einstein (14 March 1879 - 18 April 1955) was a renowned, German-born theoretical physicist who developed the theories of special and general relativity, effecting a revolution in physics. In 1924, Einstein received a paper from Bose describing his statistical model. Einstein noted that Bose's statistics also applied to some types of atoms, as well as to the proposed indistinguishable light particles, and submitted his translation of Bose's paper for publication in the Zeitschrift für Physik. Einstein also published his own articles describing the Bose statistical model and its implications, among them the condensate phenomenon that derives from the fact that the number of quantum states available for a collection of bosons at very low energy becomes exceedingly small. With less and less room for all of the particles when the temperature is decreased, they accumulate (condense) in the lowest possible (ground) energy state, as a BEC. [According to the Oxford English Dictionary, the term “Bose-Einstein Condensation” was first used in a 1938 scientific publication; Physical Review, 54 947.] Bose-Einstein statistics are now used to describe the behaviors of any assembly of bosons.

Liquid natural gas (LNG) is composed mostly of methane (80–99%). For shipping, it is chilled to -260°F, at which point it is condensed into a liquid 1/600 of its original volume. It is transported globally in this form aboard ships with insulated containers that offload it at special terminals.

LNG tankers have been around the United States since 1959, when the first cargo was exported from Lake Charles, Louisiana, to England. There are around 200 LNG tankers in service in 2007, and nearly that many more are on order at specialized shipyards to meet the globe’s growing demand for this source of energy.

LNG tankers have completed more than 40,000 voyages without serious incident; they have the best safety record of any category of commercial shipping. However, they are among the world’s most expensive and difficult ships to build.

Methane Shirley Elisabeth is one of the newest types of LNG tankers, having been delivered to its owners in March 2007. Its double hulls, separated by six feet of seawater, protect the four gas tanks, which are refrigerated and insulated to maintain the -260°F temperature. The tanks, or membranes, consist of layers of stainless steel and other materials alternating with thick foam insulation. The insides of the membranes are lined with stainless steel, corrugated in two dimensions to prevent the frozen gas from sloshing around inside.

The first successful mechanical refrigeration equipment was patented soon after the Civil War, but the large size and high cost of these early machines restricted their use to industrial processes. In his effort to improve mechanical air-conditioning systems, Willis Haviland Carrier (1876-1950) introduced the first practical centrifugal refrigeration compressor in 1922 (pictured here). This machine provided the foundation for safer, smaller, and more powerful and efficient large-scale air-conditioning systems.

Prior to the introduction of the centrifugal compressor--which compressed the refrigerant gas through the centrifugal force created by rotors spinning at high speed—reciprocating compressors compressed the refrigerant by the action of pistons inside cylinders, much like an automobile engine. The centrifugal compressor proved an extremely important advancement and paved the way for "comfort" air conditioning in theaters, department stores, hospitals, banks, offices, and hotels.

Carrier installed this initial compressor at his company's Newark, N.J., offices, where he gave the first public demonstration of the machine on May 22, 1922. Two years later, he sold the compressor to the Onondaga Pottery Company of Syracuse, N.Y., for the air conditioning of its lithography plant. The machine remained in use there until about 1957, when the Carrier Company repurchased the compressor for donation to the Smithsonian. Earlier, in 1924, the Carrier Company had installed centrifugal refrigeration machines in the J. L. Hudson department store in Detroit and the Palace Theater in Dallas, thereby introducing the phrase "air conditioning" into the public vocabulary.

This object consists of the following three components: ion source with oven and acceleration electrode; semicircular glass vacuum chamber; ion collector with two plates. The original device included an electromagnet, which is not part of this accession.

In 1939, as political tensions in Europe increased, American physicists learned of an astonishing discovery: the nucleus of the uranium atom can be split, causing the release of an immense amount of energy. Given the prospects of war, the discovery was just as worrying as it was intellectually exciting. Could the Germans use it to develop an atomic bomb?

The Americans realized that they had to determine whether a bomb was physically possible. Uranium consists mostly of the isotope U-238, with less than 1% of U-235. Theoreticians predicted that it was the nuclei of the rare U-235 isotope that undergo fission, the U-238 being inactive. To test this prediction, it was necessary to separate the two isotopes, but it would be difficult to do this since they are chemically identical.

Alfred Nier, a young physicist at the University of Minnesota, was one of the few people in the world with the expertise to carry out the separation. He used a physical technique that took advantage of the small difference in mass of the two isotopes. To separate and collect small quantities of them, he employed a mass spectrometer technique that he first developed starting in about 1937 for measurement of relative abundance of isotopes throughout the periodic table. (The basic principles of the mass spectrometer are described below.)

As a measure of the great importance of his work, in October 1939, Nier received a letter from eminent physicist Enrico Fermi, then at Columbia University, expressing great interest in whether, and how, the separation was progressing. Motivated by such urging, by late February 1940, Nier was able to produce two tiny samples of separated U-235 and U-238, which he provided to his collaborators at Columbia University, a team headed by John R. Dunning of Columbia. The Dunning team was using the cyclotron at the University in numerous studies to follow up on the news from Europe the year before on the fission of the uranium atom. In March 1940, with the samples provided by Nier, the team used neutrons produced by a proton beam from the cyclotron to show that it was the comparatively rare uranium-235 isotope that was the most readily fissile component, and not the abundant uranium-238.

The fission prediction was verified. The Nier-Dunning group remarked, "These experiments emphasize the importance of uranium isotope separation on a larger scale for the investigation of chain reaction possibilities in uranium" (reference: A.O. Nier et. al., Phys. Rev. 57, 546 (1940)). This proof that U-235 was the fissile uranium isotope opened the way to the intense U.S. efforts under the Manhattan Project to develop an atomic bomb. (For details, see Nier’s reminiscences of mass spectrometry and The Manhattan Project at: http://pubs.acs.org/doi/pdf/10.1021/ed066p385).

The Dunning cyclotron is also in the Modern Physics Collection (object id no. 1978.1074.01; catalog no. N-09130), and it will be presented on the SI collections website in 2015. (Search for “Dunning Cyclotron” at http://collections.si.edu/search/)

The Nier mass spectrometer used to collect samples of U-235 and U-238 (object id no. 1990.0446.01)

Nier designed an apparatus based on the principle of the mass spectrometer, an instrument that he had been using to measure isotopic abundance ratios throughout the entire periodic table. As in most mass spectrometers of the time, his apparatus produced positive ions by the controlled bombardment of a gas (UBr˅4, generated in a tiny oven) by an electron beam. The ions were drawn from the ionizing region and moved into an analyzer, which used an electromagnet for the separation of the various masses. Usually, the ion currents of the separated masses were measured by means of an electrometer tube amplifier, but in this case the ions simply accumulated on two small metal plates set at the appropriate positions. Nier’s mass spectrometer required that the ions move in a semicircular path in a uniform magnetic field. The mass analyzer tube was accordingly mounted between the poles of an electromagnet that weighed two tons, and required a 5 kW generator with a stabilized output voltage to power it. (The magnet and generator were not collected by the Smithsonian.) The ion source oven, 180-degree analyzer tube, and isotope collection plates are seen in the photos of the Nier apparatus (see accompanying media file images for this object).

Basic principles of the mass spectrometer

When a charged particle, such as an ion, moves in a plane perpendicular to a magnetic field, it follows a circular path. The radius of the particle’s path is proportional to the product of its mass and velocity, and is inversely proportional to the product of its electrical charge and the magnetic field strength. A mass spectrometer consists of three components: an ion source, a mass analyzer, and a detector. The ion source converts a portion of the sample into ions. There is a wide variety of ionization techniques, depending on the phase (solid, liquid, gas) of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample and gives them a selected velocity. They then pass through the magnetic field (created by an electromagnet) of the mass analyzer. For a given magnetic field strength, the differences in mass-to-charge ratio of the ions result in corresponding differences in the curvature of their circular paths through the mass analyzer. This results in a spatial sorting of the ions exiting the analyzer. The detector records either the charge induced or the current produced when an ion passes by or hits a surface, thus providing data for calculating the abundance and mass of each isotope present in the sample. For a full description with a schematic diagram of a typical mass spectrometer, go to: http://www.chemguide.co.uk/analysis/masspec/howitworks.html

In 1940, during the time that Nier separated the uranium isotopes, he developed a mass spectrometer for routine isotope and gas analysis. An instrument was needed that did not use a 2-ton magnet, or required a 5 kW voltage-stabilized generator for providing the current in the magnet coils. Nier therefore developed the sector magnet spectrometer, in which a 60-degree sector magnet took the place of the much larger one needed to give a 180-degree deflection. The result was that a magnet weighing a few hundred pounds, and powered by several automobile storage batteries, took the place of the significantly larger and heavier magnet which required a multi-kW generator. Quoting Nier, “The analyzer makes use of the well-known theorem that if ions are sent into a homogeneous magnetic field between two V-shaped poles there is a focusing action, provided the source, apex of the V, and the collector lie along a straight line” (reference: A.O. Nier, Rev. Sci. Instr., 11, 212, (1940)). This design was to become the prototype for all subsequent magnetic deflection instruments, including hundreds used in the Manhattan Project.

Thomas Edison used this carbon-filament bulb in the first public demonstration of his most famous invention, the first practical electric incandescent lamp, which took place at his Menlo Park, New Jersey, laboratory on New Year's Eve, 1879.

As the quintessential American inventor-hero, Edison personified the ideal of the hardworking self-made man. He received a record 1,093 patents and became a skilled entrepreneur. Though occasionally unsuccessful, Edison and his team developed many practical devices in his "invention factory," and fostered faith in technological progress.

Inventors seeking to develop energy-efficient lamps could not simply start with a blank piece of paper. They needed to work within the capabilities of existing lighting and power systems. Sometimes even small features had an influence, like the use of the screw-in base and socket.

What became the standard screw-in lamp base and socket was introduced by Thomas Edison in 1883, and it hasn't changed since. To this day often referred to as an "Edison base," it's formally known as the medium-screw base. While there are other base sizes (and types), the medium-screw base is the most common, especially in residential light fixtures.

Since sockets for this base are so widespread, designers of compact fluorescent lamps (CFLs) like this 1993 Panasonic "Light Capsule" needed to ensure their products would fit that size. This model EFG16LE lamp is an integral unit--it's all in one piece, including the screw-in base. Other modular lamps used specially designed plug-in bases. The plug-in base has several advantages over the medium-screw base. One of the most important is that if the light fixture takes a plug-in base, one can't use a cheap regular lamp in place of the more expensive CFL.

But few homes had fixtures with plug-in bases. And lamp makers realized that few homeowners would replace their fixtures just to use the new lamps. So inventors needed to design their lamps with the screw-base, or develop an adaptor.

After decades of constant decline, the cost of electricity in the U.S. began to rise beginning in the 1960s. The change occurred for many reasons, one of which was continually growing demand for electric power. During the 1980s electric utilities that had traditionally concerned themselves with managing the supply of power began adopting so-called Demand Side Management programs (DSM). The idea centered on encouraging the use of special pricing and greater energy efficiency to slow the need for new power plants and transmission lines.

While many DSM programs focused on commercial and industrial power users, some targeted residential consumers. One popular program involved utilities' swapping regular incandescent lamps for new, energy-efficient compact fluorescent lamps (CFLs). The participating utility purchased a large quantity of CFLs from a lamp maker at a discount and then provided the lamps to consumers at a reduced price, or sometimes for free. Some governments provided subsidies to help cover the costs.

Bulb-swaps introduced many people to energy-efficient CFLs. They also provided a market demand during the early years of CFL production when lamp makers were still paying for the new production lines needed to make the new lamps. As more lamps were produced, prices began to decline. This "Super Q'Lite" modular lamp from Lights Of America was offered by Washington, DC utility PEPCO in 1994 as part of a DSM program. Using only 27 watts, it replaced a regular lamp that used 100 watts.

Lamp characteristics: A modular compact fluorescent lamp with two parts—a tube assembly and a base-unit. The original package and coupon book were collected with this lamp. The tube assembly consists of a four-tube glass structure with two electrodes, mercury and an internal phosphor coating. Plug-in style base. The base-unit has a medium-screw shell and houses the ballast and starter equipment. A receptacle on top accepts the plug-in base of the tube assembly.

An unusual looking type of compact fluorescent lamp (CFLs) has spiral tubes, like this "Spiralux" lamp made by Duro-Test in 1996. Several manufacturers developed and now produce spiral CFLs. While the equipment to make these spiral tubes proved expensive to develop, the design addresses two problems.

CFL engineers faced a problem stemming from the fact that energy efficiency in fluorescent lamps depends in part on the distance the electric current travels between the two electrodes, called the arc path. A long arc path is more efficient than a short arc path. But most residential fixtures are designed to accept lamps the size of ordinary incandescent bulbs. So CFLs have been made with a variety of bent, folded, and connected tubes--all intended to put a long arc-path into a small lamp, the spiral design being one such.

The second problem centered on how light generated by the lamp interacted with shades and reflectors on fixtures. Most incandescent lamp fixtures are designed to use frosted or so-called soft white lamps. The coatings prevent the filament from being seen, making it look like the entire glass bulb is glowing. Shades and reflectors used in regular fixtures are designed using the science of optics to spread and direct the light in predictable patterns. CFLs, with their glowing tubes, are not shaped correctly for regular fixtures, causing light from the fixtures to be emitted in undesired patterns. Spiral CFLs closely mimic the shape of a glowing incandescent lamp so the optical design of the fixture operates as intended.

One method that companies have long used to minimize production costs is to design products that use many of the same parts. In the early 1990s Duro-Test Lighting used this approach in a series of modular compact fluorescent lamps (CFLs).

Modular CFLs are designed so that specific parts can be replaced if they fail. This allows the reuse of expensive parts that still work. In this particular lamp, the fluorescent tube and the reflector enclosing it are made as one piece; the base-unit that houses the ballast and starter are another. In addition to allowing one to replace the tube assembly if it failed, one could swap different assemblies. The reflector lamp could be changed to a decorative lamp for example, without having to remove the base-unit.

Since the price of electronic components has dropped since this lamp was made, the economic reasoning behind this feature is less persuasive.

Lamp characteristics: Two-piece, modular compact fluorescent lamp including a base-unit and a tube assembly. The base-unit has a medium-screw base-shell with plastic insulator, and a plastic skirt that houses a ballast and a starter. A socket on top accepts a plug-in base. Tube assembly includes plastic plug-in base, a fluorescent tube with two electrodes, mercury, and a phosphor coating. A glass R-shaped envelope with silvered coating serves as a reflector and is glued to the tube assembly's base.